1. Field of the Invention
The present invention relates to a blower fan and a method of manufacturing the blower fan.
2. Description of the Related Art
FIG. 2A of JP-A 2006-207578 discloses a horizontal blower 100. Paragraph [0010] of JP-A 2006-207578 states that the horizontal blower 100 is made up of a housing 102 and an impeller 108. Paragraph [0012] of JP-A 2006-207578 states that the housing 102 is made up of outer frames 102a and 102b joined to each other, and that the outer frames 102a and 102b can be joined to each other through, for example, coupling, riveting, locking, adhesion, or the like.
FIG. 4 of US 2009/0230798 discloses a fan motor 1, a plate member 2, a coupling barrel 3, and an outer case 4. Paragraph [0019] of US 2009/0230798 states that the plate member 2 is made of metal, and that the coupling barrel 3 and the outer case 4 are made of plastic. According to paragraphs [0020] and [0021] of US 2009/0230798, the coupling barrel 3, to which the fan motor 1 is attached, is coupled to a through-hole 23 of the plate member 2 through insert molding. In addition, the plate member 2 includes a plurality of positioning legs 24 arranged to extend obliquely from a periphery of the through-hole 23. The positioning legs 24 are embedded in the coupling barrel 3. According to paragraph [0022] of US 2009/0230798, the outer case 4 includes a case body 41 and a cover body 42. The cover body 42 is arranged to extend from the case body 41 to cover a side of the plate member 2 opposite to a side thereof which faces the fan motor 1.
Achieving a reduced thickness of a blower fan as described in US 2009/0230798 is not easy to perform because the cover body 42 of the outer case 4 is arranged below the plate member 2 in an overlapping manner. This being the case, regarding the blower fan of US 2009/0230798, it is only conceivable to join an edge portion of a lower plate portion, to which a motor portion is fixed, to a lower end portion of a side wall portion of a housing through insert molding. In this case, it is necessary to ensure sufficient joint strength between the lower plate portion and the side wall portion to prevent removal of the lower plate portion from the side wall portion.
Here, the blower fan is used, for example, to cool an interior of a case of a notebook personal computer (hereinafter referred to as a “notebook PC”). Regarding the notebook PC, there is a desire to avoid arranging the blower fan such that the blower fan visually stands out when the interior of the case, which is colored black, for example, is viewed through an air inlet defined in the case. It is therefore necessary that a lower surface of the lower plate portion of the blower fan should be colored black. In the case where the lower plate portion is colored black through electrodeposition coating, an outer circumferential surface of the lower plate portion is also coated with a smooth coat of paint, and therefore, only a limited increase in the joint strength between the lower plate portion and the side wall portion can be achieved because of the need to apply paint through, for example, an electrodeposition coating.